Fire alarm device



July 17, 1956 M. A. PRYOR FIRE ALARM DEVICE Filed June 29, 1954 INVENTOR A4144 5/2/45 Aaazpflas me ATTORNEY United States Patent FIRE ALARM DEVICE Malenis Adolphus Pryor, Henrico County, Va.

Application June 29, 1954, Serial No. 440,153

1 Claim. (Cl. 2059-143) This invention relates to a new and useful improve ment in a fire alarm device, and more particularly to such devices used in connection with houses and structures subjected to fire hazards.

One of the objects of this invention is the provision of a device adapted for engagement with insulated electrical wires in an electrical circuit of an alarm system.

Another object of this invention is the provision of a device adapted for engagement with insulated electrical wires in an electrical alarm circuit so as to cause an alarm when the insulation being engaged by said device is removed by fire or otherwise.

A further object of this invention is the provision of a device in electrical circuit with an alarm system, and being adapted to close said circuit when certain temperatures occur in and about said device, thereby causing the alarm to operate.

Further objects and features will more fully appear from the following description and accompanying drawings, in which:

Fig. l is a perspective view of the device engaging electrical wires,

Fig. 2 is a diagrammatic view showing the device in electrical circuit, and

Fig. 3 is a modification of the device in electrical circuit.

Referring more particularly to the drawings (Fig. l) the device consists of a pair of metal bars, legs or blades 1 and 2, provided with recesses 3 and 4 which are respectively disposed in one of the ends of said legs, and a link 5 connects said legs in pivotal fashion.

Extensions 6 and 7 respectively project from legs 1 and 2, and have disposed in the other of their ends apertures 8 and 9 into which the ends of a spring 10 pass and are anchored to said legs, as clearly illustrated in Fig. 1. The spring 10 tends to force the legs together.

Electrical insulated wires 11 and 12 are preferably wound or twisted about each other, and a portion thereof is held in clamped position between the legs.

A source of electrical energy, such as a battery 13 has one end of a wire 14 connected to the positive side of the battery and the other of its ends to an alarm or bell 15. One end of wire 11 connects with the other side of said bell, and engages said legs as aforesaid, while wire 12 has one of its ends connected to the negative side of the battery, and engages said legs, as clearly shown in Fig. 1. Wires 11 and 12 may be extended to any desired length, and the device clamped on at various points along said wires. For example, the twisted wires may be in electrical circuit from room to room of a house or building, and the device clamped on the wires in each room so that a fire starting in any part of a building may be detected.

The device functions as follows: When a fire burns off the insulation upon which the device is clamped or engaged, the legs are forced toward each other and either cause the bare wires to contact each other or the Patented July 17, 1956 legs to short circuit the wires thus causing current to flow from battery 13 through wire 14, bell 15, legs 1 or 2 or wires 11 and 12 to the negative side of the battery, thus causing the bell to alarm.

It can now be readily observed that I have produced a device comprising a pair of electrically conducting bars 1 and 2 arranged in suitably spaced opposed relation having their opposite ends connected together, respectively, and having, at least, one pair of opposite ends connected to a retracting spring 10 whereby unexpected heat can soften the insulation of said interposed wires and thereby cause said bars to sink through the softened heated insulation of said wires and make electrical contact with said wires to close the electrical circuit and operate an alarm. As an alternative operation the wires 11 and 12 may be pressed together through the softened insulation and thereby close the electrical circuit.

Referring to the modification, a rod 16 is disposed upon a bracket 17 of insulated material, and is adapted to be secured to any suitable base. The rod has extending therefrom a tapered end 18 having an aperture 19 therein whose wall is threaded. A slot 20 is located in said rod, and a metallic spring 21 has one of its ends secured therein and the other of its ends provided with an electrical contact 22. Contact 22 is held in spaced relation from a contact 23 by a spring 24 having one of its ends fastened to spring 21 and the other of its ends secured to a set-screw 25 mounted in threadable fashion in aperture 19.

A wire 26 has one of its ends connected to contact 23, and the other of its ends connected to a battery 27. A wire 28 is connected to the negative side of the battery, and one side of an alarm or bell 29. A Wire 30 is connected to the other side of the bell and spring 21.

The modification functions as follows: When spring 21 is exposed to certain temperatures of heat the former tends to expand and move into engagement with contact 23 thereby causing current to flow from battery 27 through wire 26, contacts 22 and 23, spring 21, wire 30, alarm or bell 29, and wire 28 to the negative side of the battery, thereby causing the alarm to operate. It is thought obvious that when the set-screw is turned to cause the spring 24 to expand thereby pulling spring 21 and contact 22 away from contact 23 a greater heat temperature will be required to cause contacts 22 and 23 to engage, and thus undesired high heat temperatures may be thereby anticipated and close the circuit to actuate the alarm.

Having described this invention, what is claimed is:

In a device of the character described adapted for engagement with a pair of spaced insulated wires, said device comprising a pair of electrical conductor bars arranged in opposed spaced relation to receive said Wires in interposed position between them, said bars having each pair of its opposite ends, respectively, connected together, at least, one pair of its ends being connected by a retracting spring tending to pull said bars together against said insulated wires, whereby when said insulated wires are heated said bars will sink through the softened insulation of the wires to make an electrical connection between said pair of wires.

References Cited in the file of this patent UNITED STATES PATENTS 856,727 Ruthven June 11, 1907 1,574,508 OKeetfe Feb. 23, 1926 2,518,789 Jackson Aug. 15, 1950 FOREIGN PATENTS 510,674 Germany Oct. 22, 1930 

